/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 东莞呵呵
 * Date:2022-05-04
 * Time:22:19
 */
public class TestDemo3 {
    public static void main(String[] args) {
        int [] arr={1,1,3,3,5,5,7,7,9,9,8,8,6};//6出现了一次
        int ret=0;
        for (int i = 0; i < arr.length; i++) {
            ret^=arr[i];
        }
        System.out.println(ret);
    }
}
